Shock

Shock represents hypoperfusion leading to cellular metabolic failure, with attendant clinical and biochemical markers indicating shock severity and response to therapy. While identifying and treating the underlying cause (source control for sepsis, hemostasis for exsanguination, etc) is paramount, the approach to shock is fundamentally straightforward. Assessment of volume responsiveness or volume tolerance, correction of vasoplegia, and modulation of pump function to improve forward flow aim to recover tissue perfusion at the macroscopic level and facilitate metabolic recovery. These strategies often must be applied simultaneously despite the traditionally used etiology-based classifications of shock. The intensivist should thus be familiar with a variety of invasive and noninvasive tools to determine the approach of greatest perceived yield and evaluate efficacy of interventions.  This review contains 4 figures, 1 table, and 50 references. Key Words: anaerobic metabolism, fluid responsiveness, hemorrhagic shock, lactic acidosis, measurement of intravascular volume, neurogenic shock, septic shock, shock, Swan-Ganz catheter, treatment of shock